In a substrate treatment apparatus for performing etching, chemical vapor deposition (CVD), sputtering, ion implantation, ashing, exposure, inspection, or the like, as means for adsorbing and holding an object to be adsorbed (a treatment object) such as a semiconductor wafer or a glass substrate, an electrostatic chuck is used.
The electrostatic chuck is fabricated by inserting an electrode in a ceramic dielectric substrate such as alumina and performing firing. The electrostatic chuck is for applying power for electrostatic adsorption to the built-in electrode, thereby adsorbing a substrate such as a silicon wafer by an electrostatic force.
In such a substrate treatment apparatus, for higher throughput, an increase in output of a plasma process and an increase in temperature of the plasma process are progressing. For the higher throughput, a cooling function of the object to be adsorbed is one of the main points. Further, realizing the higher throughput leads to an increase in the amount of heat which is input to the substrate treatment apparatus. For this reason, a material of a member which can be used in the electrostatic chuck is limited to a highly thermally-resistant material.
For example, for an adhesive to bond a ceramic dielectric substrate to a metal plate which supports the ceramic dielectric substrate, bonding strength between ceramic and metal at a high temperature, heat transference from the ceramic to the metal, flexibility capable of coping with shear stress due to a difference in thermal expansion, electrical insulation properties, and the like are required. While there is an adhesive having relatively high thermal conductivity or an adhesive having relatively excellent heat resistance and plasma resistance, as compared to ceramic, metal, or the like, the plasma resistance of the adhesive in the plasma process is the lowest among members which are used for the electrostatic chuck. For this reason, the life of the adhesive becomes the life of the electrostatic chuck.
If the adhesive is damaged in a process such as etching, a ceramic filler component which improves heat conduction or an elastomer component which cannot be gasified sometimes becomes a particle source. Further, if the adhesive is damaged, the thermal conductivity of the adhesive is reduced, and thus a function of heat conduction and a function of uniformly maintaining the temperature of the object to be adsorbed are not sometimes fulfilled. Therefore, an electrostatic chuck is desired in which it is possible to reduce damage to which the adhesive is subjected.